Semifinished product for electric contacts made of a composite material based on silver-tin oxide and powdermetallurgical process of making said product
AssigneeDoduco KG Dr. Eugen Durrwachter
InventorsUrsula Mayer, Roland Michal, Karl E. Saeger
Life of this patent
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Abstract
A semifinished product for electric contact made from a composite material based on silver-tin oxide is described as well as a powder-metallurgical process of making said product. The structure of the semifinished products contains regions which contain no metal oxide or very little metal oxide in alternation with regions which contain the entire metal oxide component or a greatly predominating/share thereof in a fine division.
Claims30
A powder-metallurgical process of making a semifinished product based on silver in combination with tin oxide for electric contacts comprising a composite material having 60 to 95% by weight of a first component with a high electric conductivity, namely, of silver or a silver based alloy, and
- a second component, which is insoluble in the first component and reduces the tendency of the contacts to weld and their consumption and which based on the weight of the composite material has 3 to 25% by weight of tin oxide, 0 to 10% by weight of one or more further metal oxides excluding silver oxide which together with the tin oxide comprise the metal oxide component, 0 to 10% by weight of one or more metal carbides and 0 to 10% by weight of one or more additional metals, which are insoluble in the first component,
- wherein the tin oxide predominates in the second component and the average content of the metal oxide component in the composite material is not in excess of 25% by weight,
- in that a composite powder which contains less than one-half of the first component and 60 to 100% based on the metal oxide component of the metal oxide component is mixed with one or more powders which contain the balance of the first component and of the second component, and
- the powder mixture is compacted to form shaped bodies consisting of the composite material, in which low-oxide and high-oxide regions are present in a statistically uniform distribution and the high-oxide regions are formed by the composite powder particles.
A semifinished product based on silver in combination with tin oxide for electric contacts comprising a composite material having 60 to 95% by weight of a first component with a high electric conductivity, namely, of silver or a silver based alloy and of 40 to 5% by weight of a second component, which is distributed but insoluble in the first component and reduces the tendency to weld and the consumption and which based on the weight of the composite material has 3 to 25% by weight tin oxide, 0 to 10% by weight of one or more further metal oxides excluding silver oxide which together with the tin oxide comprise the metal oxide component, 0 to 10% by weight of one or more metal carbides and 0 to 10% by weight of one or more additional metals, which are insoluble in the first component,
- wherein the tin oxide predominates in the second component and the average content of the metal oxide component in the composite material is not in excess of 25% by weight,
- characterized in that the structure of the composite material comprises low-oxide regions, in which the content of the metal oxide component is 0 to 20% of its average content and is present in a fine division in a matrix formed by the material of the first component, in alternation with high-oxide regions, in which the content of the metal oxide component is 1.5 to 6 times its average content in the semifinished product and which contains also the balance of the first component in a fine distribution of one in the other,
- wherein the low-oxide and high-oxide regions are present in the composite material in a statistically uniform distribution and the low-oxide regions surround a large part of the high-oxide regions.
Dependencies are inferred from the claim text.